Apparatus for blood pressure estimation using photoplethysmography and contact pressure

ABSTRACT

An apparatus for estimating cardiovascular information includes: a main body; and a strap connected to the main body and formed to be flexible to be wrapped around an object, wherein the main body may include: a pulse wave measurer configured to measure, from the subject, a first pulse wave signal by using a first light of a first wavelength, and a second pulse wave signal by using a second light of a second wavelength, the first wavelength being different from the second wavelength; a contact pressure measurer configured to measure a contact pressure between the object and the pulse wave measurer; and a processor configured to extract a cardiovascular characteristic value based on the first pulse wave signal, the second pulse wave signal, and change in the contact pressure, and estimate cardiovascular information based on the extracted cardiovascular characteristic value.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims priority from Korean Patent Application No.10-2017-0135384, filed on Oct. 18, 2017, and Korean Patent ApplicationNo. 10-2018-0111192, filed on Sep. 18, 2018, in the Korean IntellectualProperty Office, the disclosures of which are incorporated herein byreference in their entireties.

BACKGROUND 1. Field

Apparatuses and methods consistent with exemplary embodiments relate toestimating cardiovascular information.

2. Description of the Related Art

Generally, a cuff-based measurement method and a cuffless measurementmethod are used as a non-invasive method of estimating cardiovascularinformation such as blood pressure and the like. The cuff-basedmeasurement method includes: a method of measuring blood pressure bywinding a cuff around an upper arm and hearing the sound of bloodvessels through a stethoscope during inflation and deflation of thecuff; and an Oscillometric method which includes measuring pressuresignals during inflation/deflation of the cuff using an automated deviceand measuring blood pressure based on a point of maximum pressure signalchange. As the cuffless measurement method, there is a Pulse TransitTime (PTT) method of estimating blood pressure by using pulse wavevelocity, and a Pulse Wave Analysis (PWA) method of estimating bloodpressure by pulse wave form analysis.

According to the cuff-based measurement method, cuff pressure may causepain to a subject. In the cuffless measurement method, including PTTmethod and the PWA method, blood pressure is estimated based on pulsewaves, such that accuracy of measurement cannot be guaranteed.

SUMMARY

Exemplary embodiments address at least the above problems and/ordisadvantages and other disadvantages not described above. Also, theexemplary embodiments are not required to overcome the disadvantagesdescribed above, and may not overcome any of the problems describedabove.

One or more exemplary embodiments provide an apparatus and method forestimating cardiovascular information.

According to an aspect of an exemplary embodiment, there is provided anapparatus for estimating cardiovascular information including: a pulsewave measurer configured to measure, from an object, a first pulse wavesignal by using a first light of a first wavelength and a second pulsewave signal by using a second light of a second wavelength, the firstwavelength being different from the second wavelength; a contactpressure measurer configured to measure a contact pressure between theobject and the pulse wave measurer; and a processor configured toextract a cardiovascular characteristic value based on the first pulsewave signal, the second pulse wave signal, and a change in the contactpressure, and estimate cardiovascular information based on the extractedcardiovascular characteristic value.

The pulse wave measurer may include: a light source configured to emitthe first light and the second light onto the object; and aphotodetector configured to measure the first pulse wave signal and thesecond pulse wave signal by receiving the first light and the secondlight which are reflected or scattered from the object, respectively.

The contact pressure measurer may measure the contact pressure by usingat least one of a force sensor, a pressure sensor, an accelerationsensor, a piezoelectric film, a load cell, radar, and aphotoplethysmography (PPG) sensor.

The processor may detect a contact pressure transition period based onthe contact pressure, may extract at least one pulse wave feature pointbased on the first pulse wave signal and the second pulse wave signal inthe contact pressure transition period, and may extract thecardiovascular characteristic value by using at least one of a pulsewave characteristic value and a contact pressure value which correspondto the at least one pulse wave feature point.

The contact pressure transition period may include a contact pressureincreasing period and a contact pressure decreasing period.

The processor may extract, as the at least one pulse wave feature point,at least one of a valley point and a peak point of a first pulse wavedirect current (DC) component signal in the contact pressure transitionperiod, a valley point and a peak point of a second pulse wave DCcomponent signal in the contact pressure transition period, a valleypoint and a peak point of a differentiated first pulse wave DC componentsignal in the contact pressure transition period, a valley point and apeak point of a differentiated second pulse wave DC component signal inthe contact pressure transition period, a valley point and a peak pointof a first pulse wave alternating current (AC) component signal in thecontact pressure transition period, a valley point and a peak point of asecond pulse wave AC component signal in the contact pressure transitionperiod, a valley point and a peak point of a DC component differentialsignal in the contact pressure transition period, and a valley point anda peak point of a differentiated DC component differential signal in thecontact pressure transition period.

The processor may extract the cardiovascular characteristic value basedon at least one of T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12,T13, T14, T15, T16, T17, T18, T19, T20, T21, T22, T23, T24, A1, A2, A3,A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18,A19, A20, A21, A22, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12,P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, P23, P24, Pgmax, andPgmin of the first pulse wave signal and the second pulse wave signal.

T1 may denote time of a valley point of a first pulse wave DC componentsignal in a contact pressure increasing period; T2 may denote time of apeak point of a first pulse wave DC component signal in the contactpressure increasing period; T3 may denote time of a valley point of asecond pulse wave DC component signal in the contact pressure increasingperiod; T4 may denote time of a peak point of the second pulse wave DCcomponent signal in the contact pressure increasing period; T5 maydenote time of a valley point of the first pulse wave DC componentsignal in a contact pressure decreasing period; T6 may denote time of apeak point of the first pulse wave DC component signal in the contactpressure decreasing period; T7 may denote time of a valley point of thesecond pulse wave DC component signal in the contact pressure decreasingperiod; T8 may denote time of a peak point of the second pulse wave DCcomponent signal in the contact pressure decreasing period; T9 maydenote time of a valley point of a differentiated first pulse wave DCcomponent signal in the contact pressure increasing period; T10 maydenote time of a valley point of the differentiated second pulse wave DCcomponent signal in the contact pressure increasing period; T11 maydenote time of a peak point of the differentiated first pulse wave DCcomponent signal in the contact pressure decreasing period; T12 maydenote time of a peak point of the differentiated second pulse wave DCcomponent signal in the contact pressure decreasing period; T13 maydenote time of a peak point of a first pulse wave AC component signal ina contact pressure increasing period; T14 may denote time of a peakpoint of the second pulse wave AC component signal in the contactpressure increasing period; T15 may denote time of a valley point of afirst pulse wave AC component signal in a contact pressure decreasingperiod; T16 may denote time of a valley point of the second pulse waveAC component signal in a contact pressure decreasing period; T17 maydenote time of a peak point of a DC component differential signal in thecontact pressure increasing period; T18 may denote time of a valleypoint of the DC component differential signal in the contact pressureincreasing period; T19 may denote time of a peak point of adifferentiated DC component differential signal in the contact pressureincreasing period; T20 may denote time of a valley point of the DCcomponent differential signal in the contact pressure decreasing period;T21 may denote time of a peak point of a DC component differentialsignal in the contact pressure decreasing period; T22 may denote time ofa valley point of the differentiated DC component differential signal inthe contact pressure decreasing period; T23 may denote time when thecontract pressure starts to increase; T24 may denote time when thecontract pressure starts to decrease; A1 may denote an amplitude of thefirst pulse wave DC component signal at T1; A2 may denote an amplitudeof the first pulse wave DC component signal at T2; A3 may denote anamplitude of the second pulse wave DC component signal at T3; A4 maydenote an amplitude of the second pulse wave DC component signal at T4;A5 may denote an amplitude of the first pulse wave DC component signalat T5; A6 may denote an amplitude of the first pulse wave DC componentsignal at T6; A7 may denote an amplitude of the second pulse wave DCcomponent signal at T7; A8 may denote an amplitude of the second pulsewave DC component signal at T8; A9 may denote an amplitude of thedifferentiated first pulse wave DC component signal at T9; A10 maydenote an amplitude of the differentiated second pulse wave DC componentsignal T10; A11 may denote an amplitude of the differentiated firstpulse wave DC component signal T11; A12 may denote an amplitude of thedifferentiated second pulse wave DC component signal T12; A13 may denotean amplitude of the first pulse wave AC component signal T13; A14 maydenote an amplitude of the second pulse wave AC component signal at T14;A15 may denote an amplitude of the first pulse wave AC component signalat T15; A16 may denote an amplitude of the second pulse wave ACcomponent signal at T16; A17 may denote an amplitude of the DC componentdifferential signal at T17; A18 may denote an amplitude of the DCcomponent differential signal at T18; A19 may denote an amplitude of thedifferentiated DC component differential signal at T19; A20 may denotean amplitude of the DC component differential signal at T20; A21 maydenote an amplitude of the DC component differential signal at T21; A22may denote an amplitude of the differentiated DC component differentialsignal at T22; P1 may denote a contact pressure magnitude at T1; P2 maydenote a contact pressure magnitude at T2; P3 may denote a contactpressure magnitude at T3; P4 may denote a contact pressure magnitude atT4; P5 may denote a contact pressure magnitude at T5; P6 may denote acontact pressure magnitude at T6; P7 may denote a contact pressuremagnitude at T7; P8 may denote a contact pressure magnitude at T8; P9may denote a contact pressure magnitude at T9; P10 may denote a contactpressure magnitude at T10; P11 may denote a contact pressure magnitudeat T11; P12 may denote a contact pressure magnitude at T12; P13 maydenote a contact pressure magnitude at T13; P14 may denote a contactpressure magnitude at T14; P15 may denote a contact pressure magnitudeat T15; P16 may denote a contact pressure magnitude at T16; P17 maydenote a contact pressure magnitude at T17; P18 may denote a contactpressure magnitude at T18; P19 may denote a contact pressure magnitudeat T19; P20 may denote a contact pressure magnitude at T20; P21 maydenote a contact pressure magnitude at T21; P22 may denote a contactpressure magnitude at T22; P23 may denote a contact pressure magnitudeat T23; P24 may denote a contact pressure magnitude at T24; Pgmax maydenote a maximum value of a contact pressure gradient in the contactpressure increasing period; and Pgmin may denote a minimum value of acontact pressure gradient in the contact pressure decreasing period.

The cardiovascular information may include at least one of bloodpressure, vascular age, arterial stiffness, cardiac output, vascularcompliance, blood glucose, blood triglycerides, and peripheral vascularresistance.

The object may be a user of the apparatus, and the processor maygenerate guide information for guiding the user to increase or decreasethe contact pressure.

The apparatus for estimating cardiovascular information may furtherinclude an actuator configured to control the contact pressure betweenthe object and the pulse wave measurer.

The apparatus for estimating cardiovascular information may furtherinclude a communication interface configured to transmit, to an externaldevice, at least one of the first pulse wave signal, the second pulsewave signal, the contact pressure, the pulse wave feature point, thecardiovascular characteristic value, and the cardiovascular information.

The apparatus for estimating cardiovascular information may furtherinclude an output interface configured to output the cardiovascularinformation to an external device.

The apparatus for estimating cardiovascular information may beimplemented in one of a cellular phone, a smartphone, a tablet personalcomputer (PC), a laptop computer, a personal digital assistant (PDA), aportable multimedia player (PMP), a navigation, an MP3 player, a digitalcamera, and a wearable device.

According to an aspect of another exemplary embodiment, there isprovided a wearable device including: a main body; and a strap connectedto the main body and formed to be flexible to be wrapped around anobject, wherein the main body may include: a pulse wave measurerconfigured to measure, from the subject, a first pulse wave signal byusing a first light of a first wavelength, and a second pulse wavesignal by using a second light of a second wavelength, the firstwavelength being different from the second wavelength; a contactpressure measurer configured to measure a contact pressure between theobject and the pulse wave measurer; and a processor configured toextract a cardiovascular characteristic value based on the first pulsewave signal, the second pulse wave signal, and a change in the contactpressure, and estimate cardiovascular information based on the extractedcardiovascular characteristic value.

The processor may detect a contact pressure transition period based onthe contact pressure, may extract at least one pulse wave feature pointbased on the first pulse wave signal and the second pulse wave signal inthe contact pressure transition period, and may extract thecardiovascular characteristic value by using at least one of a pulsewave characteristic value and a contact pressure value which correspondto the at least one pulse wave feature point.

The main body may further include an actuator configured to control thecontact pressure between the object and the pulse wave measurer byadjusting a length of the strap.

According to an aspect of another exemplary embodiment, there isprovided a method of estimating cardiovascular information by using apulse wave measurer. The method may include: measuring a first pulsewave signal from an object by using a first light of a first wavelength;measuring a second pulse wave signal from the object by using a secondlight of a second wavelength; measuring a contact pressure between theobject and the pulse wave measurer; extracting a cardiovascularcharacteristic value based on the first pulse wave signal, the secondpulse wave signal, and a change in the contact pressure; and estimatingcardiovascular information based on the extracted cardiovascularcharacteristic value.

The measuring the first pulse wave signal and the measuring the secondpulse wave signal may include: emitting the first light and the secondlight onto the object; and measuring the first pulse wave signal and thesecond pulse wave signals by receiving the first light and the secondlight which are reflected or scattered from the object, respectively.

The measuring the first pulse wave signal and the second pulse wavesignal may include: emitting light of different wavelengths onto theobject; and measuring the pulse wave signals by receiving lightreflected or scattered from the object.

The measuring the contact pressure may include measuring the contactpressure by using at least one of a force sensor, a pressure sensor, anacceleration sensor, a piezoelectric film, a load cell, radar, and aphotoplethysmography (PPG) sensor.

The extracting the cardiovascular characteristic value may include:detecting a contact pressure transition period based on the contactpressure; extracting at least one pulse wave feature point based on thefirst pulse wave signal and the second pulse wave signal in the contactpressure transition period; and extracting the cardiovascularcharacteristic value by using at least one of a pulse wavecharacteristic value and a contact pressure value which correspond tothe at least one pulse wave feature point.

The contact pressure transition period may include a contact pressureincreasing period and a contact pressure decreasing period.

The extracting the at least one pulse wave feature point may includeextracting, as the at least one pulse wave feature point, at least oneof a valley point and a peak point of a first pulse wave DC componentsignal in the contact pressure transition period, a valley point and apeak point of a second pulse wave DC component signal in the contactpressure transition period, a valley point and a peak point of adifferentiated first pulse wave DC component signal in the contactpressure transition period, a valley point and a peak point of adifferentiated second pulse wave DC component signal in the contactpressure transition period, a valley point and a peak point of a firstpulse wave AC component signal in the contact pressure transitionperiod, a valley point and a peak point of a second pulse wave ACcomponent signal in the contact pressure transition period, a valleypoint and a peak point of a DC component differential signal in thecontact pressure transition period, and a valley point and a peak pointof a differentiated DC component differential signal in the contactpressure transition period.

The extracting of the cardiovascular characteristic value may includeextracting the cardiovascular characteristic value by combining at leastone or two or more of T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12,T13, T14, T15, T16, T17, T18, T19, T20, T21, T22, T23, T24, A1, A2, A3,A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14, A15, A16, A17, A18,A19, A20, A21, A22, P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12,P13, P14, P15, P16, P17, P18, P19, P20, P21, P22, P23, P24, Pgmax, andPgmin of the first pulse wave signal and the second pulse wave signal.

T1 may denote time of a valley point of a first pulse wave DC componentsignal in a contact pressure increasing period; T2 may denote time of apeak point of a first pulse wave DC component signal in the contactpressure increasing period; T3 may denote time of a valley point of asecond pulse wave DC component signal in the contact pressure increasingperiod; T4 may denote time of a peak point of the second pulse wave DCcomponent signal in the contact pressure increasing period; T5 maydenote time of a valley point of the first pulse wave DC componentsignal in a contact pressure decreasing period; T6 may denote time of apeak point of the first pulse wave DC component signal in the contactpressure decreasing period; T7 may denote time of a valley point of thesecond pulse wave DC component signal in the contact pressure decreasingperiod; T8 may denote time of a peak point of the second pulse wave DCcomponent signal in the contact pressure decreasing period; T9 maydenote time of a valley point of a differentiated first pulse wave DCcomponent signal in the contact pressure increasing period; T10 maydenote time of a valley point of the differentiated second pulse wave DCcomponent signal in the contact pressure increasing period; T11 maydenote time of a peak point of the differentiated first pulse wave DCcomponent signal in the contact pressure decreasing period; T12 maydenote time of a peak point of the differentiated second pulse wave DCcomponent signal in the contact pressure decreasing period; T13 maydenote time of a peak point of a first pulse wave AC component signal ina contact pressure increasing period; T14 may denote time of a peakpoint of the second pulse wave AC component signal in the contactpressure increasing period; T15 may denote time of a valley point of afirst pulse wave AC component signal in a contact pressure decreasingperiod; T16 may denote time of a valley point of the second pulse waveAC component signal in a contact pressure decreasing period; T17 maydenote time of a peak point of a DC component differential signal in thecontact pressure increasing period; T18 may denote time of a valleypoint of the DC component differential signal in the contact pressureincreasing period; T19 may denote time of a peak point of adifferentiated DC component differential signal in the contact pressureincreasing period; T20 may denote time of a valley point of the DCcomponent differential signal in the contact pressure decreasing period;T21 may denote time of a peak point of a DC component differentialsignal in the contact pressure decreasing period; T22 may denote time ofa valley point of the differentiated DC component differential signal inthe contact pressure decreasing period; T23 may denote time when thecontract pressure starts to increase; T24 may denote time when thecontract pressure starts to decrease; A1 may denote an amplitude of thefirst pulse wave DC component signal at T1; A2 may denote an amplitudeof the first pulse wave DC component signal at T2; A3 may denote anamplitude of the second pulse wave DC component signal at T3; A4 maydenote an amplitude of the second pulse wave DC component signal at T4;A5 may denote an amplitude of the first pulse wave DC component signalat T5; A6 may denote an amplitude of the first pulse wave DC componentsignal at T6; A7 may denote an amplitude of the second pulse wave DCcomponent signal at T7; A8 may denote an amplitude of the second pulsewave DC component signal at T8; A9 may denote an amplitude of thedifferentiated first pulse wave DC component signal at T9; A10 maydenote an amplitude of the differentiated second pulse wave DC componentsignal T10; A11 may denote an amplitude of the differentiated firstpulse wave DC component signal T11; A12 may denote an amplitude of thedifferentiated second pulse wave DC component signal T12; A13 may denotean amplitude of the first pulse wave AC component signal T13; A14 maydenote an amplitude of the second pulse wave AC component signal at T14;A15 may denote an amplitude of the first pulse wave AC component signalat T15; A16 may denote an amplitude of the second pulse wave ACcomponent signal at T16; A17 may denote an amplitude of the DC componentdifferential signal at T17; A18 may denote an amplitude of the DCcomponent differential signal at T18; A19 may denote an amplitude of thedifferentiated DC component differential signal at T19; A20 may denotean amplitude of the DC component differential signal at T20; A21 maydenote an amplitude of the DC component differential signal at T21; A22may denote an amplitude of the differentiated DC component differentialsignal at T22; P1 may denote a contact pressure magnitude at T1; P2 maydenote a contact pressure magnitude at T2; P3 may denote a contactpressure magnitude at T3; P4 may denote a contact pressure magnitude atT4; P5 may denote a contact pressure magnitude at T5; P6 may denote acontact pressure magnitude at T6; P7 may denote a contact pressuremagnitude at T7; P8 may denote a contact pressure magnitude at T8; P9may denote a contact pressure magnitude at T9; P10 may denote a contactpressure magnitude at T10; P11 may denote a contact pressure magnitudeat T11; P12 may denote a contact pressure magnitude at T12; P13 maydenote a contact pressure magnitude at T13; P14 may denote a contactpressure magnitude at T14; P15 may denote a contact pressure magnitudeat T15; P16 may denote a contact pressure magnitude at T16; P17 maydenote a contact pressure magnitude at T17; P18 may denote a contactpressure magnitude at T18; P19 may denote a contact pressure magnitudeat T19; P20 may denote a contact pressure magnitude at T20; P21 maydenote a contact pressure magnitude at T21; P22 may denote a contactpressure magnitude at T22; P23 may denote a contact pressure magnitudeat T23; P24 may denote a contact pressure magnitude at T24; Pgmax maydenote a maximum value of a contact pressure gradient in the contactpressure increasing period; and Pgmin may denote a minimum value of acontact pressure gradient in the contact pressure decreasing period.

The cardiovascular information may include at least one of bloodpressure, vascular age, arterial stiffness, cardiac output, vascularcompliance, blood glucose, blood triglycerides, and peripheral vascularresistance.

The object may be a user of the pulse wave measure, and the method ofestimating cardiovascular information may further include generating andoutputting guide information about an action of the user for estimatingthe cardiovascular information.

The method of estimating cardiovascular information may further includecontrolling the contact pressure between the object and the pulse wavemeasurer.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects will be more apparent by describingcertain exemplary embodiments, with reference to the accompanyingdrawings, in which:

FIG. 1 is a block diagram illustrating an apparatus for estimatingcardiovascular information according to an exemplary embodiment;

FIG. 2 is a block diagram illustrating a processor according to anexemplary embodiment;

FIG. 3 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to an exemplaryembodiment;

FIG. 4 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment;

FIG. 5 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment;

FIG. 6 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment;

FIG. 7 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment;

FIG. 8 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment;

FIG. 9 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment;

FIG. 10 is a block diagram illustrating a processor according to anotherexemplary embodiment;

FIG. 11 is a diagram illustrating guide information according to anexemplary embodiment;

FIG. 12 is a diagram illustrating guide information according to anotherexemplary embodiment;

FIG. 13 is a block diagram illustrating an apparatus for estimatingcardiovascular information according to another exemplary embodiment;

FIG. 14 is a flowchart illustrating a method of estimatingcardiovascular information according to an exemplary embodiment;

FIG. 15 is a flowchart illustrating a method of extractingcardiovascular characteristic values according to an exemplaryembodiment;

FIG. 16 is a flowchart illustrating a method of estimatingcardiovascular information according to another exemplary embodiment;

FIG. 17 is a flowchart illustrating a method of estimatingcardiovascular information according to another exemplary embodiment;and

FIG. 18 is a perspective diagram of a wrist-type wearable deviceaccording to an exemplary embodiment.

DETAILED DESCRIPTION

Exemplary embodiments are described in greater detail below withreference to the accompanying drawings.

In the following description, like drawing reference numerals are usedfor like elements, even in different drawings. The matters defined inthe description, such as detailed construction and elements, areprovided to assist in a comprehensive understanding of the exemplaryembodiments. However, it is apparent that the exemplary embodiments canbe practiced without those specifically defined matters. Also,well-known functions or constructions are not described in detail sincethey would obscure the description with unnecessary detail.

Process steps described herein may be performed differently from aspecified order, unless a specified order is clearly stated in thecontext of the disclosure. That is, each step may be performed in aspecified order, at substantially the same time, or in a reverse order.

It will be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another. Any references to singular may include pluralunless expressly stated otherwise. In the present specification, itshould be understood that the terms, such as ‘including’ or ‘having.’etc., are intended to indicate the existence of the features, numbers,steps, actions, components, parts, or combinations thereof disclosed inthe specification, and are not intended to preclude the possibility thatone or more other features, numbers, steps, actions, components, parts,or combinations thereof may exist or may be added.

Expressions such as “at least one of.” when preceding a list ofelements, modify the entire list of elements and do not modify theindividual elements of the list. For example, the expression, “at leastone of a, b, and c,” should be understood as including only a, only b,only c, both a and b, both a and c, both b and c, all of a, b, and c, orany variations of the aforementioned examples.

Further, components that will be described in the specification arediscriminated merely according to functions mainly performed by thecomponents. That is, two or more components which will be describedlater can be integrated into a single component. Furthermore, a singlecomponent which will be explained later can be separated into two ormore components. Moreover, each component which will be described canadditionally perform some or all of a function executed by anothercomponent in addition to the main function thereof. Some or all of themain function of each component which will be explained can be carriedout by another component. Each component may be implemented in hardwareor software, or a combination thereof.

FIG. 1 is a block diagram illustrating an apparatus for estimatingcardiovascular information according to an exemplary embodiment. Theapparatus 100 for estimating cardiovascular information may be embeddedin an electronic device. In particular, examples of the electronicdevice may include a cellular phone, a smartphone, a tablet PC, a laptopcomputer, a personal digital assistant (PDA), a portable multimediaplayer (PMP), a navigation, an MP3 player, a digital camera, a wearabledevice, and the like; and examples of the wearable device may include awristwatch-type wearable device, a wristband-type wearable device, aring-type wearable device, a waist belt-type wearable device, anecklace-type wearable device, an ankle band-type wearable device, athigh band-type wearable device, a forearm band-type wearable device,and the like. However, the examples of the electronic device and thewearable device are not limited thereto.

Referring to FIG. 1, the apparatus 100 for estimating cardiovascularinformation includes a pulse wave measurer 110, a contact pressuremeasurer 120, and a processor 130.

The pulse wave measurer 110 may measure a first pulse wave signal and asecond pulse wave signal from an object by using light of differentwavelengths. To this end, the pulse wave measurer 110 includes a lightsource 111 may emit light of different wavelengths onto an object. Thefirst pulse wave signal and the second pulse wave signal may have afirst wavelength band and a second wavelength band, respectively, whichare different from each other. The first wavelength band may partiallyoverlap with the second wavelength band, or may be separated from thesecond wavelength band.

The light source 111 may emit light of different wavelengths. Forexample, the light source 111 may emit visible light or infrared lightonto an object. However, wavelengths of light emitted by the lightsource 111 may vary according to a purpose of measurement and the like.Further, the light source 111 may include a single light emitting body,or an array of a plurality of light emitting bodies. In the case wherethe light source 111 is configured as an array of a plurality of lightemitting bodies, the plurality of light emitting bodies may emit lightof different wavelengths according to the purpose of measurement, or allthe light emitting bodies may emit light of the same wavelength. In oneexemplary embodiment, the light source 111 may include a light emittingdiode (LED), a laser diode, or the like. However, this is merelyexemplary, and the light source 111 is not limited thereto

Further, the light source 111 may further include at least one opticalelement for directing the emitted light toward a desired position of anobject.

The photodetector 112 may measure a pulse wave signal by receiving lightreflected or scattered from the object. In one exemplary embodiment, thephotodetector 112 may include a photo diode, a photo transistor (PTr), acharge-coupled device (CCD), and the like. The photodetector 112 may beformed as a single device, or an array of a plurality of devices.

The contact pressure measurer 120 may measure contact pressure betweenthe object and the pulse wave measurer 110. In one exemplary embodiment,the contact pressure measurer 120 may measure contact pressure betweenthe object and the pulse wave measurer 1110 by using a force sensor, apressure sensor, an acceleration sensor, a piezoelectric film, a loadcell, radar, a photoplethysmography (PPG) sensor, and the like.

The processor 130 may extract cardiovascular characteristic values basedon the first pulse wave signal, the second pulse wave signal, and thecontact pressure, and may estimate cardiovascular information based onthe extracted cardiovascular characteristic values. For example, theprocessor 130 may extract at least one pulse wave feature point based onthe first pulse wave signal and the second pulse wave signal in acontact pressure increasing period or a contact pressure decreasingperiod, and may extract cardiovascular characteristic values by using apulse wave characteristic value, a contact pressure value, and the likewhich correspond to the extracted at least one pulse wave feature point.Further, the processor 130 may estimate cardiovascular information basedon the extracted cardiovascular characteristic values. In this case, thecardiovascular characteristics may refer to characteristics associatedwith cardiovascular information desired to be estimated, and thecardiovascular information may include blood pressure, vascular age,arterial stiffness, cardiac output, vascular compliance, blood glucose,blood triglycerides, peripheral vascular resistance, and the like.

Hereinafter, the processor will be described in detail with reference toFIG. 2.

FIG. 2 is a block diagram illustrating a processor according to anexemplary embodiment. The processor 200 of FIG. 2 may be an example ofthe processor 130 of FIG. 1.

Referring to FIG. 2, the processor 200 includes a feature pointextractor 210, a cardiovascular characteristic value extractor 220, acardiovascular information estimator 230, and a cardiovascularinformation estimation model 240. In FIG. 2, the cardiovascularinformation estimation model 240 is illustrated as part of the processor100, but the present exemplary embodiment is not limited thereto. Forexample, the cardiovascular information estimation model 240 may bestored on a storage separately provided from the processor 100.

The feature point extractor 210 may detect a contact pressure increasingperiod or a contact pressure decreasing period based on a measuredcontact pressure value. The contact pressure increasing period and thecontact pressure decreasing period may be referred to as a contactpressure transition period. The feature point extractor 210 may extractat least one pulse wave feature point based on a first pulse wave signaland a second pulse wave signal in the contact pressure transitionperiod. In one exemplary embodiment, the feature point extractor 210 mayextract, as pulse wave feature points, a valley point and a peak pointof a direct current (DC) component signal of the first pulse wave signalin the contact pressure transition period (hereinafter referred to as afirst pulse wave DC component signal), a valley point and a peak pointof a DC component signal of the second pulse wave signal in the contactpressure transition period (hereinafter referred to as a second pulsewave DC component signal), a valley point and a peak point of a signalgenerated by differentiating the first pulse wave DC component signal inthe contact pressure transition period (hereinafter referred to as adifferentiated first pulse wave DC component signal), a valley point anda peak point of a signal generated by differentiating the second pulsewave DC component signal in the contact pressure transition period(hereinafter referred to as a differentiated second pulse wave DCcomponent signal), a valley point and a peak point of an alternatingcurrent (AC) component signal of the first pulse wave signal in thecontact pressure transition period (hereinafter referred to as a firstpulse wave AC component signal), a valley point and a peak point of anAC component signal of the second pulse wave signal in the contactpressure transition period (hereinafter referred to as a second pulsewave AC component signal), a valley point and a peak point of adifferential signal of the first pulse wave DC component signal and thesecond pulse wave DC component signal in the contact pressure transitionperiod (hereinafter referred to as a DC component differential signal),a valley point and a peak point of a signal generated by differentiatingthe DC component differential signal in the contact pressure transitionperiod (hereinafter referred to as a differentiated DC componentdifferential signal), and the like.

The cardiovascular characteristic value extractor 220 may extractcardiovascular characteristic values based on the extracted at least onepulse wave feature point.

In one exemplary embodiment, the cardiovascular characteristic valueextractor 220 may extract cardiovascular characteristic values by usinga pulse wave characteristic value and/or a contact pressure value whichcorrespond to the extracted at least one pulse wave feature point. Forexample, the cardiovascular characteristic value extractor 220 mayextract cardiovascular characteristic values by linearly or non-linearlycombining at least one or two or more of T1, T2, T3, T4, T5, T6, T7, T8,T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22,T23, T24, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14,A15, A16, A17, A18, A19, A20, A21, A22, P1, P2, P3, P4, P5, P6, P7, P8,P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22,P23, P24, Pgmax, and Pgmin. Here, T1 denotes time of a valley point of afirst pulse wave DC component signal in a contact pressure increasingperiod; T2 denotes time of a peak point of a first pulse wave DCcomponent signal in a contact pressure increasing period; T3 denotestime of a valley point of a second pulse wave DC component signal in acontact pressure increasing period; T4 denotes time of a peak point of asecond pulse wave DC component signal in a contact pressure increasingperiod; T5 denotes time of a valley point of a first pulse wave DCcomponent signal in a contact pressure decreasing period; T6 denotestime of a peak point of a first pulse wave DC component signal in acontact pressure decreasing period; T7 denotes time of a valley point ofa second pulse wave DC component signal in a contact pressure decreasingperiod; T8 denotes time of a peak point of a second pulse wave DCcomponent signal in a contact pressure decreasing period; T9 denotestime of a valley point of a differentiated first pulse wave DC componentsignal in a contact pressure increasing period; T10 denotes time of avalley point of a differentiated second pulse wave DC component signalin a contact pressure increasing period; T11 denotes time of a peakpoint of a differentiated first pulse wave DC component signal in acontact pressure decreasing period; T12 denotes time of a peak point ofa differentiated second pulse wave DC component signal in a contactpressure decreasing period; T13 denotes time of a peak point of a firstpulse wave AC component signal in a contact pressure increasing period;T14 denotes time of a peak point of a second pulse wave AC componentsignal in a contact pressure increasing period; T15 denotes time of avalley point of a first pulse wave AC component signal in a contactpressure decreasing period; T16 denotes time of a valley point of asecond pulse wave AC component signal in a contact pressure decreasingperiod; T17 denotes time of a peak point of a DC component differentialsignal in a contact pressure increasing period; T18 denotes time of avalley point of a DC component differential signal in a contact pressureincreasing period; T19 denotes time of a peak point of a differentiatedDC component differential signal in a contact pressure increasingperiod; T20 denotes time of a valley point of a DC componentdifferential signal in a contact pressure decreasing period; T21 denotestime of a peak point of a DC component differential signal in a contactpressure decreasing period; T22 denotes time of a valley point of adifferentiated DC component differential signal in a contact pressuredecreasing period; T23 denotes time when contract pressure starts toincrease; T24 denotes time when contract pressure starts to decrease; A1denotes an amplitude of the first pulse wave DC component signal at T1;A2 denotes an amplitude of the first pulse wave DC component signal atT2; A3 denotes an amplitude of the second pulse wave DC component signalat T3; A4 denotes an amplitude of the second pulse wave DC componentsignal at T4; A5 denotes an amplitude of the first pulse wave DCcomponent signal at T5; A6 denotes an amplitude of the first pulse waveDC component signal at T6; A7 denotes an amplitude of the second pulsewave DC component signal at T7; A8 denotes an amplitude of the secondpulse wave DC component signal at T8; A9 denotes an amplitude of thedifferentiated first pulse wave DC component signal at T9; A10 denotesan amplitude of the differentiated second pulse wave DC component signalT10; A11 denotes an amplitude of the differentiated first pulse wave DCcomponent signal T11; A12 denotes an amplitude of the differentiatedsecond pulse wave DC component signal T12; A13 denotes an amplitude ofthe first pulse wave AC component signal T13; A14 denotes an amplitudeof the second pulse wave AC component signal at T14; A15 denotes anamplitude of the first pulse wave AC component signal at T15; A16denotes an amplitude of the second pulse wave AC component signal atT16; A17 denotes an amplitude of the DC component differential signal atT17; A18 denotes an amplitude of the DC component differential signal atT18; A19 denotes an amplitude of the differentiated DC componentdifferential signal at T19; A20 denotes an amplitude of the DC componentdifferential signal at T20; A21 denotes an amplitude of the DC componentdifferential signal at T21; A22 denotes an amplitude of thedifferentiated DC component differential signal at T22; P1 denotes acontact pressure magnitude at T1; P2 denotes a contact pressuremagnitude at T2; P3 denotes a contact pressure magnitude at T3; P4denotes a contact pressure magnitude at T4; P5 denotes a contactpressure magnitude at T5; P6 denotes a contact pressure magnitude at T6;P7 denotes a contact pressure magnitude at T7; P8 denotes a contactpressure magnitude at T8; P9 denotes a contact pressure magnitude at T9;P10 denotes a contact pressure magnitude at T10; P11 denotes a contactpressure magnitude at T11; P12 denotes a contact pressure magnitude atT12; P13 denotes a contact pressure magnitude at T13; P14 denotes acontact pressure magnitude at T14; P15 denotes a contact pressuremagnitude at T15; P16 denotes a contact pressure magnitude at T16; P17denotes a contact pressure magnitude at T17; P18 denotes a contactpressure magnitude at T18; P19 denotes a contact pressure magnitude atT19; P20 denotes a contact pressure magnitude at T20; P21 denotes acontact pressure magnitude at T21; P22 denotes a contact pressuremagnitude at T22; P23 denotes a contact pressure magnitude at T23; P24denotes a contact pressure magnitude at T24; Pgmax denotes a maximumvalue of a contact pressure gradient in the contact pressure increasingperiod; and Pgmin denotes a minimum value of a contact pressure gradientin the contact pressure decreasing period.

The cardiovascular information estimator 230 may estimate cardiovascularinformation of an object based on the extracted cardiovascularcharacteristic values. In particular, the cardiovascular information mayinclude blood pressure, vascular age, arterial stiffness, cardiacoutput, vascular compliance, blood glucose, blood triglycerides,peripheral vascular resistance, and the like.

In one exemplary embodiment, the cardiovascular information estimator230 may estimate cardiovascular information by using the cardiovascularinformation estimation model 240 which represents a correlation betweencardiovascular characteristic values and cardiovascular information. Forexample, the cardiovascular information estimation model 240 may begenerated in the form of a mathematical algorithm, a table, and thelike, and may be stored in an internal or external database of theprocessor 200.

Hereinafter, various examples of pulse wave feature points andcardiovascular characteristic values will be described with reference toFIGS. 3 to 9.

FIG. 3 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to an exemplaryembodiment. In FIG. 3, reference numeral 310 refers to a first pulsewave DC component signal; reference numeral 320 refers to a second pulsewave DC component signal; reference numeral 330 refers to a contactpressure signal; reference numeral 340 refers to a differentiated firstpulse wave DC component signal in a contact pressure increasing period370; reference numeral 350 refers to a differentiated second pulse waveDC component signal in the contact pressure increasing period 370; andreference numeral 360 refers to a contact pressure signal in the contactpressure increasing period 370, which is time-aligned with thedifferentiated first pulse wave DC component signal 340 and thedifferentiated second pulse wave DC component signal 350. Further, thefirst pulse wave signal and the second pulse wave signal may be signalsmeasured while contact pressure between an object and the pulse wavemeasurer increases and then decreases (e.g., during a period of timewhen a user touches the pulse wave measurer with a finger and then takesthe finger off the pulse wave measurer).

Referring to FIGS. 2 and 3, the feature point extractor 210 may generatethe first pulse wave DC component signal 310 and the second pulse waveDC component signal 320 by applying a low pass filter to the first pulsewave signal and the second pulse wave signal. Further, the feature pointextractor 210 may detect the contact pressure increasing period 370based on the measured contact pressure 330, and may generate thedifferentiated first pulse wave DC component signal 340 and thedifferentiated second pulse wave DC component signal 350 bydifferentiating the first pulse wave DC component signal 310 and thesecond pulse wave DC component signal 320 in the contact pressureincreasing period 370.

The feature point extractor 210 may extract, as pulse wave featurepoints, a valley point a of the differentiated first pulse wave DCcomponent signal 340 and a valley point b of the differentiated secondpulse wave DC component signal 350.

The cardiovascular characteristic value extractor 220 may extract thetime T9 corresponding to the valley point a of the differentiated firstpulse wave DC component signal 340 and the contact pressure P9 at thetime T9, and the time T10 corresponding to the valley point b of thedifferentiated second pulse wave DC component signal 350 and the contactpressure P10 at the time T10, and may extract a value obtained by(P9−P10)/(T9−T10) or |P9−P10|/|T9−T10| as a cardiovascularcharacteristic value.

FIG. 4 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment. In FIG. 4, reference numeral 410 refers to a first pulsewave DC component signal; reference numeral 420 refers to a second pulsewave DC component signal; reference numeral 430 refers to a contactpressure signal; reference numeral 440 refers to a differentiated firstpulse wave DC component signal in a contact pressure decreasing period470; reference numeral 450 refers to a differentiated second pulse waveDC component signal in the contact pressure decreasing period 470; andreference numeral 460 refers to a contact pressure signal in the contactpressure decreasing period 470, which is time-aligned with thedifferentiated first pulse wave DC component signal 440 and thedifferentiated second pulse wave DC component signal 450. Further, thefirst pulse wave signal and the second pulse wave signal may be signalsmeasured while contact pressure between an object and the pulse wavemeasurer increases and then decreases (e.g., during a period of timewhen a user touches the pulse wave measurer with a finger and then takesthe finger off the pulse wave measurer).

Referring to FIGS. 2 and 4, the feature point extractor 210 may generatethe first pulse wave DC component signal 410 and the second pulse waveDC component signal 420 by applying a low pass filter to the first pulsewave signal and the second pulse wave signal. Further, the feature pointextractor 210 may detect the contact pressure decreasing period 470based on the measured contact pressure 430, and may generate thedifferentiated first pulse wave DC component signal 440 and thedifferentiated second pulse wave DC component signal 450 bydifferentiating the first pulse wave DC component signal 410 and thesecond pulse wave DC component signal 420 in the contact pressuredecreasing period 470.

The feature point extractor 210 may extract, as pulse wave featurepoints, a peak point c of the differentiated first pulse wave DCcomponent signal 440 and a peak point d of the differentiated secondpulse wave DC component signal 450.

The cardiovascular characteristic value extractor 220 may extract thetime T11 corresponding to the peak point c of the differentiated firstpulse wave DC component signal 440 and the contact pressure P11 at thetime T11, and the time T12 corresponding to the peak point d of thedifferentiated second pulse wave DC component signal 450 and the contactpressure P12 at the time T12, and may extract a value obtained by(P11−P12)/(T11−T12) or |P11−P12|/|T11−T12| as a cardiovascularcharacteristic value.

FIG. 5 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment. In FIG. 5, reference numeral 510 refers to a first pulsewave AC component signal; reference numeral 520 refers to a second pulsewave AC component signal; reference numeral 530 refers to a contactpressure signal; reference numeral 540 refers to a first pulse wave ACcomponent signal in a contact pressure increasing period 570; referencenumeral 550 refers to a second pulse wave AC component signal in thecontact pressure increasing period 570; and reference numeral 560 refersto a contact pressure signal in the contact pressure increasing period570, which is time-aligned with the first pulse wave AC component signal540 and the second pulse wave AC component signal 550. Further, thefirst pulse wave signal and the second pulse wave signal may be signalsmeasured while contact pressure between an object and the pulse wavemeasurer increases and then decreases (e.g., during a period of timewhen a user touches the pulse wave measurer with a finger and then takesthe finger off the pulse wave measurer).

Referring to FIGS. 2 and 5, the feature point extractor 210 may generatethe first pulse wave AC component signal 510 and the second pulse waveAC component signal 520 by applying a band pass filter to the firstpulse wave signal and the second pulse wave signal. Further, the featurepoint extractor 210 may detect the contact pressure increasing period570 based on the measured contact pressure 530, and may extract thefirst pulse wave AC component signal 540 and the second pulse wave ACcomponent signal 550 in the contact pressure increasing period 570.

The feature point extractor 210 may extract, as pulse wave featurepoints, a peak point e of the first pulse wave AC component signal 540and a peak point f of the second pulse wave AC component signal 550.

The cardiovascular characteristic value extractor 220 may extract thetime T13 corresponding to the peak point e of the first pulse wave ACcomponent signal 540 and the contact pressure P13 at the time T13, andthe time T14 corresponding to the peak point f of the second pulse waveAC component signal 550 and the contact pressure P14 at the time T14,and may extract a value obtained by (P13−P14)/(T13−T14) or|P13−P14|/|T13−T14| as a cardiovascular characteristic value.

FIG. 6 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment. In FIG. 6, reference numeral 610 refers to a first pulsewave AC component signal; reference numeral 620 refers to a second pulsewave AC component signal; reference numeral 630 refers to a contactpressure signal; reference numeral 640 refers to a first pulse wave ACcomponent signal in a contact pressure decreasing period 670; referencenumeral 650 refers to a second pulse wave AC component signal in thecontact pressure decreasing period 670; and reference numeral 660 refersto a contact pressure signal in the contact pressure decreasing period670, which is time-aligned with the first pulse wave AC component signal640 and the second pulse wave AC component signal 650. Further, thefirst pulse wave signal and the second pulse wave signal may be signalsmeasured while contact pressure between an object and the pulse wavemeasurer increases and then decreases (e.g., during a period of timewhen a user touches the pulse wave measurer with a finger and then takesthe finger off the pulse wave measurer).

Referring to FIGS. 2 and 6, the feature point extractor 210 may generatethe first pulse wave AC component signal 610 and the second pulse waveAC component signal 620 by applying a band pass filter to the firstpulse wave signal and the second pulse wave signal. Further, the featurepoint extractor 210 may detect the contact pressure decreasing period670 based on the measured contact pressure 630, and may extract thefirst pulse wave AC component signal 640 and the second pulse wave ACcomponent signal 650 in the contact pressure decreasing period 670.

The feature point extractor 210 may extract, as pulse wave featurepoints, a valley point g of the first pulse wave AC component signal 640and a valley point h of the second pulse wave AC component signal 650.

The cardiovascular characteristic value extractor 220 may extract thetime T15 corresponding to the valley point g of the first pulse wave ACcomponent signal 640 and the contact pressure P15 at the time T15, andthe time T16 corresponding to the valley point h of the second pulsewave AC component signal 650 and the contact pressure P16 at the timeT16, and may extract a value obtained by (P15−P16)/(T15−T16) or|P15−P16|/|T15−T16| as a cardiovascular characteristic value.

FIG. 7 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment. In FIG. 7, reference numeral 710 refers to a first pulsewave DC component signal; reference numeral 720 refers to a second pulsewave DC component signal; reference numeral 730 refers to a contactpressure signal; reference numeral 740 refers to a DC componentdifferential signal in a contact pressure increasing period 770;reference numeral 750 refers to a differentiated DC componentdifferential signal in the contact pressure increasing period 770; andreference numeral 760 refers to a contact pressure signal in the contactpressure increasing period 770, which is time-aligned with the DCcomponent differential signal 740 and the differentiated DC componentdifferential signal 750. Further, the first pulse wave signal and thesecond pulse wave signal may be signals measured while contact pressurebetween an object and the pulse wave measurer increases and thendecreases (e.g., during a period of time when a user touches the pulsewave measurer with a finger and then takes the finger off the pulse wavemeasurer).

Referring to FIGS. 2 and 7, the feature point extractor 210 may generatethe first pulse wave DC component signal 710 and the second pulse waveDC component signal 720 by applying a low pass filter to the first pulsewave signal and the second pulse wave signal. Further, the feature pointextractor 210 may generate the DC component differential signal 740 bysubtracting the second pulse wave DC component signal 720 in the contactpressure increasing period 770 from the first pulse wave DC componentsignal 710 in the contact pressure increasing period 770, and maygenerate the differentiated DC component differential signal 750 bydifferentiating the DC component differential signal.

The feature point extractor 210 may extract, as pulse wave featurepoints, a peak point i of the DC component differential signal 740 and apeak point j of the differentiated DC component differential signal 750.

The cardiovascular characteristic value extractor 220 may extract thetime T17 corresponding to the peak point i of the DC componentdifferential signal 740 and the contact pressure P17 at the time T17,and the time T19 corresponding to the peak point j of the differentiatedDC component differential signal 750 and the contact pressure P19 at thetime T19, and may extract a value obtained by (P17−P19)/(T17−T19) or|P17−P19|/|T17−T19| as a cardiovascular characteristic value.

FIG. 8 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment. In FIG. 8, reference numeral 810 refers to a first pulsewave DC component signal; reference numeral 820 refers to a second pulsewave DC component signal; and reference numeral 830 refers to a contactpressure signal. Further, the first pulse wave signal and the secondpulse wave signal may be signals measured while contact pressure betweenan object and the pulse wave measurer increases and then decreases(e.g., during a period of time when a user touches the pulse wavemeasurer with a finger and then takes the finger off the pulse wavemeasurer).

Referring to FIGS. 2 and 8, the feature point extractor 210 may generatethe first pulse wave DC component signal 810 and the second pulse waveDC component signal 820 by applying a low pass filter to the first pulsewave signal and the second pulse wave signal. Further, the feature pointextractor 210 may detect a contact pressure increasing period 870 and acontact pressure decreasing period 880 based on the measured contactpressure 830. In addition, the feature point extractor 210 may extract,as pulse wave feature points, a point of maximum change of the firstpulse wave DC component signal 810 and a point of maximum change of thesecond pulse wave DC component signal 820 in the contact pressureincreasing period 870; and a point of maximum change of the first pulsewave DC component signal 810 and a point of maximum change of the secondpulse wave DC component signal 820 in the contact pressure decreasingperiod 880. For example, the feature point extractor 210 may generate adifferentiated first pulse wave DC component signal and a differentiatedsecond pulse wave DC component signal in the contact pressure transitionperiods 870 and 880 by differentiating the first pulse wave DC componentsignal 810 and the second pulse wave DC component signal 820 in thecontact pressure transition periods 870 and 880. Then, the feature pointextractor 210 may extract, as pulse wave feature points, a valley pointof the differentiated first pulse wave DC component signal and a valleypoint of the differentiated second pulse wave DC component signal in thecontact pressure increasing period 870; and a peak point of thedifferentiated first pulse wave DC component signal and a peak point ofthe differentiated second pulse wave DC component signal in the contactpressure decreasing period 880.

The cardiovascular characteristic value extractor 220 may extract, ascardiovascular characteristic values, a gradient A9 at the point of thenegative maximum change of the first pulse wave DC component signal 810in the contact pressure increasing period 870 (amplitude of a valleypoint of the differentiated first pulse wave DC component signal in thecontact pressure increasing period); a gradient A11 at the point of thepositive maximum change of the first pulse wave DC component signal 810in the contact pressure decreasing period 880 (amplitude of a peak pointof the differentiated first pulse wave DC component signal in thecontact pressure decreasing period); a gradient A10 at the point of thenegative maximum change of the second pulse wave DC component signal 820in the contact pressure increasing period 870 (amplitude of a valleypoint of the differentiated second pulse wave DC component signal in thecontact pressure increasing period); a gradient A12 at the point of thepositive maximum change of the second pulse wave DC component signal 820in the contact pressure decreasing period 880 (amplitude of a peak pointof the differentiated second pulse wave DC component signal in thecontact pressure decreasing period); a gradient Pgmax of the point ofthe positive maximum change of contact pressure in the contact pressureincreasing period 870; and a gradient Pgmin of the point of the negativemaximum change of contact pressure in the contact pressure decreasingperiod 880. In addition, the cardiovascular characteristic valueextractor 220 may extract a value obtained by (A9−A10)/Pgmax,(|A9|−|A10|)/Pgmax, |A9−A10|/Pgmax, or ∥A9|−|A10∥/Pgmax, as acardiovascular characteristic value. Also, the cardiovascularcharacteristic value extractor 220 may extract a value obtained by(A11−A12)/Pgmin, (|A11|−|A12|)/Pgmin, |A11−A12|/Pgmin, or∥A11|−|A12∥/Pgmin as a cardiovascular characteristic value.

FIG. 9 is a diagram illustrating pulse wave feature points andcardiovascular characteristic values according to another exemplaryembodiment. In FIG. 9, reference numeral 910 refers to a first pulsewave DC component signal; reference numeral 920 refers to a second pulsewave DC component signal; reference numeral 930 refers to a contactpressure signal; reference numeral 940 refers to a first pulse wave DCcomponent signal in a contact pressure decreasing period 980; referencenumeral 950 refers to a second pulse wave DC component signal in thecontact pressure decreasing period 980; and reference numeral 960 refersto a DC component differential signal in the contact pressure decreasingperiod 980; reference numeral 970 refers to a contact pressure signal inthe contact pressure decreasing period 980, which is time-aligned withthe first pulse wave DC component signal 940, the second pulse wave DCcomponent signal 950, and the DC component differential signal 960.Further, the first pulse wave signal and the second pulse wave signalmay be signals measured while contact pressure between an object and thepulse wave measurer increases and then decreases (e.g., during a periodof time when a user touches the pulse wave measurer with a finger andthen takes the finger off the pulse wave measurer).

Referring to FIGS. 2 and 9, the feature point extractor 210 may generatethe first pulse wave DC component signal 910 and the second pulse waveDC component signal 920 by applying a low pass filter to the first pulsewave signal and the second pulse wave signal. Further, the feature pointextractor 210 may detect a contact pressure decreasing period 980 basedon the measured contact pressure 930; and may generate the DC componentdifferential signal 960 by subtracting the second pulse wave DCcomponent signal 950 in the contact pressure decreasing period 980 fromthe first pulse wave DC component signal 940 in the contact pressuredecreasing period 980.

The feature point extractor 210 may extract, as pulse wave featurepoints, a peak point k and a valley point l of the first pulse wave DCcomponent signal 940, a peak point m and a valley point n of the secondpulse wave DC component signal 950, and a peak point o and a valleypoint p of the DC component differential signal 960.

The cardiovascular characteristic value extractor 220 may extract, ascardiovascular characteristic values: the time T6 corresponding to thepeak point k of the first pulse wave DC component signal 940; the timeT5 corresponding to the valley point l of the first pulse wave DCcomponent signal 940; the time T8 corresponding to the peak point m ofthe second pulse wave DC component signal 950; the time T7 correspondingto the valley point n of the second pulse wave DC component signal 950;the time T21 corresponding to the peak point o of the DC componentdifferential signal 960; the time T20 corresponding to the valley pointp of the DC component differential signal 960; the time T24 when contactpressure starts to decrease; and the gradient Pgmin of a maximum changepoint of contact pressure in the contact pressure decreasing period 980.In addition, the cardiovascular characteristic value extractor 220 mayextract a value obtained by (T6−T5)/Pgmin, a value obtained by(T8−T7)/Pgmin, a value obtained by (T21−T20)/Pgmin, a value obtained by(T6−T24)/Pgmin, a value obtained by (T8−T24)/Pgmin, a value obtained by(T21−T24)/Pgmin, and the like.

FIG. 10 is a block diagram illustrating a processor according to anotherexemplary embodiment. The processor 1000 of FIG. 10 may be anotherexample of the processor 130 of FIG. 1.

Referring to FIG. 10, the processor 100 includes a feature pointextractor 210, a cardiovascular characteristic value extractor 220, acardiovascular information estimator 230, a guide information generator1010, and a model generator 1020. Here, the feature point extractor 210,the cardiovascular characteristic value extractor 220 and thecardiovascular information estimator 230 are described above withreference to FIG. 2, such that detailed description thereof will beomitted.

The guide information generator 1010 may generate guide information forguiding a user to increase or decrease contact pressure.

The model generator 1020 may generate a cardiovascular informationestimation model 240 which represents a correlation betweencardiovascular characteristic values and cardiovascular information. Inparticular, the cardiovascular information estimation model 240 may begenerated in the form of a mathematical algorithm, a table, and thelike, to estimate cardiovascular information from cardiovascularcharacteristic values. In FIG. 10, the cardiovascular informationestimation model 240 is illustrated as being stored in the processor200, but the present exemplary embodiment is not limited thereto. Forexample, the cardiovascular information estimation model 240 may bestored on a storage separately provided from the processor 200.

In one exemplary embodiment, the model generator 1020 may collectlearning data associated with cardiovascular characteristic values andcardiovascular information corresponding thereto, and may generate thecardiovascular information estimation model by regression analysis or bymachine learning using the collected learning data. In this case,examples of the regression analysis algorithm may include simple linearregression, multi linear regression, logistic regression, proportionalCox regression, and the like. Examples of the machine learning mayinclude Artificial Neural Network, Decision Tree, Genetic Algorithm,Genetic Programming, K-Nearest Neighbor, Radial Basis Function Network,Random Forest, Support Vector Machine, deep-learning, and the like.

FIG. 11 is a diagram illustrating an example of guide information, whichis generated when an apparatus for estimating cardiovascular informationis embedded in a cellular phone, a smartphone, a tablet PC, a laptopcomputer, a personal digital assistant (PDA), a portable multimediaplayer (PMP), a navigation, an MP3 player, a digital camera, and thelike.

Referring to FIG. 11, the guide information may prompt a user to performthe following two steps: a first step of increasing contact pressurebetween an object and a pulse wave measurer by rapidly touching a sensorwith a finger; and a second step of decreasing the contact pressurebetween the object and the pulse wave measurer by rapidly relaxing thefinger pressure on the sensor.

FIG. 12 is a diagram illustrating another example of guide information,which is generated when an apparatus for estimating cardiovascularinformation is embedded in a wrist-type wearable device.

Referring to FIG. 12, the guide information may prompt a user to performthe following two steps: a first step of increasing contact pressurebetween an object and a pulse wave measurer by rapidly clenching thefist while wearing the wrist-type wearable device; and a second step ofdecreasing contact pressure between the object and the pulse wavemeasurer by rapidly opening the hand after clenching the fist whilewearing the wrist-type wearable device.

FIG. 13 is a block diagram illustrating another example of an apparatusfor estimating cardiovascular information. The apparatus 1300 forestimating cardiovascular information of FIG. 13 may be embedded in anelectronic device. In this case, examples of the electronic device mayinclude a cellular phone, a smartphone, a tablet PC, a laptop computer,a personal digital assistant (PDA), a portable multimedia player (PMP),a navigation, an MP3 player, a digital camera, a wearable device, andthe like; and examples of the wearable device may include awristwatch-type wearable device, a wristband-type wearable device, aring-type wearable device, a waist belt-type wearable device, anecklace-type wearable device, an ankle band-type wearable device, athigh band-type wearable device, a forearm band-type wearable device,and the like. However, the electronic device is not limited thereto, andthe wearable device is neither limited thereto.

Referring to FIG. 13, the apparatus 1300 for estimating cardiovascularinformation includes a pulse wave measurer 110, a contact pressuremeasurer 120, a processor 130, an input interface 1310, a storageinterface 1320, a communication interface 1330, an output interface1340, and an actuator 1350. Here, the pulse wave measurer 110, thecontact pressure measurer 120, and the processor 130 are described abovewith reference to FIGS. 1 to 12, such that detailed description thereofwill be omitted.

The input interface 1310 may receive input of various operation signalsfrom a user. In one exemplary embodiment, the input interface 1310 mayinclude a keypad, a dome switch, a touch pad (staticpressure/capacitance), a jog wheel, a jog switch, a hardware (H/W)button, and the like. Particularly, the touch pad, which forms a layerstructure with a display, may be called a touch screen.

The storage interface 1320 may store programs or commands for operationof the apparatus 1300 for estimating cardiovascular information, and maystore data input to and output from the apparatus 1300 for estimatingcardiovascular information. Further, the storage interface 1320 maystore a first pulse wave signal and a second pulse wave signal which aremeasured by the pulse wave measurer 110, contact pressure measured bythe contact pressure measurer 120, pulse wave feature points andcardiovascular characteristic values which are extracted by theprocessor 130, cardiovascular information estimated by the processor130, guide information generated by the processor 130, a cardiovascularinformation estimation model, and the like.

The storage interface 1320 may include at least one storage medium of aflash memory type memory, a hard disk type memory, a multimedia cardmicro type memory, a card type memory (e.g., an SD memory, an XD memory,etc.), a Random Access Memory (RAM), a Static Random Access Memory(SRAM), a Read Only Memory (ROM), an Electrically Erasable ProgrammableRead Only Memory (EEPROM), a Programmable Read Only Memory (PROM), amagnetic memory, a magnetic disk, and an optical disk, and the like.Further, the apparatus 1300 for estimating cardiovascular informationmay operate an external storage medium, such as web storage and thelike, which performs a storage function of the storage interface 1320 onthe Internet.

The communication interface 1330 may perform communication with anexternal device. For example, the communication interface 1330 maytransmit, to the external device, data input by a user through the inputinterface 1310, the first pulse wave signal and second pulse wave signalwhich are measured by the pulse wave measurer 110, the contact pressuremeasured by the contact pressure measurer 120, the pulse wave featurepoints and cardiovascular characteristic values which are extracted bythe processor 130, the cardiovascular information estimated by theprocessor 130, the guide information generated by the processor 130, thecardiovascular information estimation model, and the like, or mayreceive, from the external device, various data useful for estimatingcardiovascular information.

In particular, the external device may be medical equipment using thefirst pulse wave signal and second pulse wave signal which are measuredby the pulse wave measurer 110, the contact pressure measured by thecontact pressure measurer 120, the pulse wave feature points andcardiovascular characteristic values which are extracted by theprocessor 130, the cardiovascular information estimated by the processor130, the guide information generated by the processor 130, thecardiovascular information estimation model, and the like, a printer toprint out results, or a display to display the results. In addition, theexternal device may be a digital TV, a desktop computer, a cellularphone, a smartphone, a tablet PC, a laptop computer, a personal digitalassistant (PDA), a portable multimedia player (PMP), a navigation, anMP3 player, a digital camera, a wearable device, and the like, but isnot limited thereto.

The communication interface 1330 may communicate with an external deviceby using Bluetooth communication, Bluetooth Low Energy (BLE)communication, Near Field Communication (NFC), WLAN communication,Zigbee communication, Infrared Data Association (IrDA) communication,Wi-Fi Direct (WFD) communication, Ultra-Wideband (UWB) communication,Ant+ communication, WIFI communication, Radio Frequency Identification(RFID) communication, 3G communication, 4G communication, 5Gcommunication, and the like. However, this is merely exemplary and isnot intended to be limiting.

The output interface 1340 may output the first pulse wave signal andsecond pulse wave signal which are measured by the pulse wave measurer110, the contact pressure measured by the contact pressure measurer 120,the pulse wave feature points and cardiovascular characteristic valueswhich are extracted by the processor 130, the cardiovascular informationestimated by the processor 130, the guide information generated by theprocessor 130, the cardiovascular information estimation model, and thelike. In one exemplary embodiment, the output interface 1340 may outputthe first pulse wave signal and second pulse wave signal which aremeasured by the pulse wave measurer 110, the contact pressure measuredby the contact pressure measurer 120, the pulse wave feature points andcardiovascular characteristic values which are extracted by theprocessor 130, the cardiovascular information estimated by the processor130, the guide information generated by the processor 130, thecardiovascular information estimation model, and the like, by using atleast one of an acoustic method, a visual method, and a tactile method.To this end, the output interface 1340 may include a display, a speaker,a vibrator, and the like.

The actuator 1350 may control contact pressure between an object and thepulse wave measurer 110. For example, the actuator 1350 may increase thecontact pressure between the object and the pulse wave measurer 110 to apredetermined level, and after maintaining the contact pressure at thelevel for a predetermined period of time, the actuator 1350 may decreasethe contact pressure.

FIG. 14 is a flowchart illustrating an example of a method of estimatingcardiovascular information. The method of estimating cardiovascularinformation of FIG. 14 may be performed by the apparatus 100 forestimating cardiovascular information of FIG. 1.

Referring to FIGS. 1 and 14, the apparatus 100 for estimatingcardiovascular information may measure a first pulse wave signal and asecond pulse wave signal by using light of different wavelengths inoperation 1410. For example, the apparatus 100 for estimatingcardiovascular information may emit light of different wavelengths ontoan object, and may measure the first pulse wave signal and the secondpulse wave signal by receiving light reflected or scattered from theobject. The first pulse wave signal and the second pulse wave signal mayhave a first wavelength band and a second wavelength band, respectively,which are different from each other. The first wavelength band maypartially overlap with the second wavelength band, or may be separatedfrom the second wavelength band.

The apparatus 100 for estimating cardiovascular information may measurecontact pressure between the object and the pulse wave measurer inoperation 1420. In one exemplary embodiment, the apparatus 100 forestimating cardiovascular information may measure contact pressurebetween the object and the pulse wave measurer by using a force sensor,a pressure sensor, an acceleration sensor, a piezoelectric film, a loadcell, radar, a photoplethysmography (PPG) sensor, and the like.

The apparatus 100 for estimating cardiovascular information may extractcardiovascular characteristic values based on the first pulse wavesignal, the second pulse wave signal, and the contact pressure inoperation 1430, and may estimate cardiovascular information based on theextracted cardiovascular characteristic values in operation 1440. Inthis case, the cardiovascular characteristics may refer tocharacteristics associated with cardiovascular information desired to beestimated, and the cardiovascular information may include bloodpressure, vascular age, arterial stiffness, cardiac output, vascularcompliance, blood glucose, blood triglycerides, peripheral vascularresistance, and the like.

FIG. 15 is a flowchart illustrating a method of extractingcardiovascular characteristic values according to an exemplaryembodiment. The method of extracting cardiovascular characteristicvalues may be an example of the method of extracting cardiovascularcharacteristic values in 1430 of FIG. 14.

Referring to FIGS. 1 and 15, the apparatus 100 for estimatingcardiovascular information may detect a contact pressure transitionperiod based on contact pressure in operation 1510. The contact pressuretransition period may include a contact pressure increasing period and acontact pressure decreasing period.

The apparatus 100 for estimating cardiovascular information may extractat least one pulse wave feature point based on the first pulse wavesignal and the second pulse wave signal in the contact pressuretransition period in operation 1520. For example, the apparatus 100 forestimating cardiovascular information may extract, as pulse wave featurepoints, a valley point and a peak point of a first pulse wave DCcomponent signal in the contact pressure transition period, a valleypoint and a peak point of a second pulse wave DC component signal in thecontact pressure transition period, a valley point and a peak point of adifferentiated first pulse wave DC component signal in the contactpressure transition period, a valley point and a peak point of adifferentiated second pulse wave DC component signal in the contactpressure transition period, a valley point and a peak point of a firstpulse wave AC component signal in the contact pressure transitionperiod, a valley point and a peak point of a second pulse wave ACcomponent signal in the contact pressure transition period, a valleypoint and a peak point of a DC component differential signal in thecontact pressure transition period, a valley point and a peak point of adifferentiated DC component differential signal in the contact pressuretransition period, and the like.

The apparatus 100 for estimating cardiovascular information may extractcardiovascular characteristic values based on the extracted at least onepulse wave feature point in operation 1530. In one exemplary embodiment,the apparatus 100 for estimating cardiovascular information may extractcardiovascular characteristic values by using a pulse wavecharacteristic value, a contact pressure value, and the like whichcorrespond to the extracted at least one pulse wave feature point. Forexample, the apparatus 100 for estimating cardiovascular information mayextract cardiovascular characteristic values by linearly or non-linearlycombining at least one or two or more of T1, T2, T3, T4, T5, T6, T7, T8,T9, T10, T11, T12, T13, T14, T15, T16, T17, T18, T19, T20, T21, T22,T23, T24, A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14,A15, A16, A17, A18, A19, A20, A21, A22, P1, P2, P3, P4, P5, P6, P7, P8,P9, P10, P11, P12, P13, P14, P15, P16, P17, P18, P19, P20, P21, P22,P23, P24, Pgmax, and Pgmin. Here, T1 denotes time of a valley point of afirst pulse wave DC component signal in a contact pressure increasingperiod; T2 denotes time of a peak point of a first pulse wave DCcomponent signal in a contact pressure increasing period; T3 denotestime of a valley point of a second pulse wave DC component signal in acontact pressure increasing period; T4 denotes time of a peak point of asecond pulse wave DC component signal in a contact pressure increasingperiod; T5 denotes time of a valley point of a first pulse wave DCcomponent signal in a contact pressure decreasing period; T6 denotestime of a peak point of a first pulse wave DC component signal in acontact pressure decreasing period; T7 denotes time of a valley point ofa second pulse wave DC component signal in a contact pressure decreasingperiod; T8 denotes time of a peak point of a second pulse wave DCcomponent signal in a contact pressure decreasing period; T9 denotestime of a valley point of a differentiated first pulse wave DC componentsignal in a contact pressure increasing period; T10 denotes time of avalley point of a differentiated second pulse wave DC component signalin a contact pressure increasing period; T11 denotes time of a peakpoint of a differentiated first pulse wave DC component signal in acontact pressure decreasing period; T12 denotes time of a peak point ofa differentiated second pulse wave DC component signal in a contactpressure decreasing period; T13 denotes time of a peak point of a firstpulse wave AC component signal in a contact pressure increasing period;T14 denotes time of a peak point of a second pulse wave AC componentsignal in a contact pressure increasing period; T15 denotes time of avalley point of a first pulse wave AC component signal in a contactpressure decreasing period; T16 denotes time of a valley point of asecond pulse wave AC component signal in a contact pressure decreasingperiod; T17 denotes time of a peak point of a DC component differentialsignal in a contact pressure increasing period; T18 denotes time of avalley point of a DC component differential signal in a contact pressureincreasing period; T19 denotes time of a peak point of a differentiatedDC component differential signal in a contact pressure increasingperiod; T20 denotes time of a valley point of a DC componentdifferential signal in a contact pressure decreasing period; T21 denotestime of a peak point of a DC component differential signal in a contactpressure decreasing period; T22 denotes time of a valley point of adifferentiated DC component differential signal in a contact pressuredecreasing period; T23 denotes time when contract pressure starts toincrease; T24 denotes time when contract pressure starts to decrease; A1denotes an amplitude of the first pulse wave DC component signal at T1;A2 denotes an amplitude of the first pulse wave DC component signal atT2; A3 denotes an amplitude of the second pulse wave DC component signalat T3; A4 denotes an amplitude of the second pulse wave DC componentsignal at T4; A5 denotes an amplitude of the first pulse wave DCcomponent signal at T5; A6 denotes an amplitude of the first pulse waveDC component signal at T6; A7 denotes an amplitude of the second pulsewave DC component signal at T7; A8 denotes an amplitude of the secondpulse wave DC component signal at T8; A9 denotes an amplitude of thedifferentiated first pulse wave DC component signal at T9; A10 denotesan amplitude of the differentiated second pulse wave DC component signalT10; A11 denotes an amplitude of the differentiated first pulse wave DCcomponent signal T11; A12 denotes an amplitude of the differentiatedsecond pulse wave DC component signal T12; A13 denotes an amplitude ofthe first pulse wave AC component signal T13; A14 denotes an amplitudeof the second pulse wave AC component signal at T14; A15 denotes anamplitude of the first pulse wave AC component signal at T15; A16denotes an amplitude of the second pulse wave AC component signal atT16; A17 denotes an amplitude of the DC component differential signal atT17; A18 denotes an amplitude of the DC component differential signal atT18; A19 denotes an amplitude of the differentiated DC componentdifferential signal at T19; A20 denotes an amplitude of the DC componentdifferential signal at T20; A21 denotes an amplitude of the DC componentdifferential signal at T21; A22 denotes an amplitude of thedifferentiated DC component differential signal at T22; P1 denotes acontact pressure magnitude at T1; P2 denotes a contact pressuremagnitude at T2; P3 denotes a contact pressure magnitude at T3; P4denotes a contact pressure magnitude at T4; P5 denotes a contactpressure magnitude at T5; P6 denotes a contact pressure magnitude at T6;P7 denotes a contact pressure magnitude at T7; P8 denotes a contactpressure magnitude at T8; P9 denotes a contact pressure magnitude at T9;P10 denotes a contact pressure magnitude at T10; P11 denotes a contactpressure magnitude at T11; P12 denotes a contact pressure magnitude atT12; P13 denotes a contact pressure magnitude at T13; P14 denotes acontact pressure magnitude at T14; P15 denotes a contact pressuremagnitude at T15; P16 denotes a contact pressure magnitude at T16; P17denotes a contact pressure magnitude at T17; P18 denotes a contactpressure magnitude at T18; P19 denotes a contact pressure magnitude atT19; P20 denotes a contact pressure magnitude at T20; P21 denotes acontact pressure magnitude at T21; P22 denotes a contact pressuremagnitude at T22; P23 denotes a contact pressure magnitude at T23; P24denotes a contact pressure magnitude at T24; Pgmax denotes a maximumvalue of a contact pressure gradient in the contact pressure increasingperiod; and Pgmin denotes a minimum value of a contact pressure gradientin the contact pressure decreasing period.

FIG. 16 is a flowchart illustrating a method of estimatingcardiovascular information according to another exemplary embodiment.The method of estimating cardiovascular information of FIG. 16 may beperformed by the apparatus 100 for estimating cardiovascular informationof FIG. 1.

Referring to FIGS. 1 and 16, the apparatus 100 for estimatingcardiovascular information may generate and output guide information forguiding a user to increase or decrease contact pressure in operation1610. For example, the apparatus 100 for estimating cardiovascularinformation may generate guide information illustrated in FIGS. 11 and12.

The apparatus 100 for estimating cardiovascular information may measurea first pulse wave signal and a second pulse wave signal from an objectby using light of different wavelengths in operation 1620, and maymeasure contact pressure between the object and the pulse wave measurerin operation 1630.

The apparatus 100 for estimating cardiovascular information may extractcardiovascular characteristic values based on the first pulse wavesignal, the second pulse wave signal, and the contact pressure inoperation 1640, and may estimate cardiovascular information based on theextracted cardiovascular characteristic values in operation 1650.

FIG. 17 is a flowchart illustrating a method of estimatingcardiovascular information according to another exemplary embodiment.The method of estimating cardiovascular information of FIG. 17 may beperformed by the apparatus 1300 for estimating cardiovascularinformation of FIG. 13.

Referring to FIGS. 13 and 17, the apparatus 1300 for estimatingcardiovascular information may control contact pressure between anobject and a pulse wave measurer by using an actuator in operation 1710.For example, the apparatus 1300 for estimating cardiovascularinformation may increase the contact pressure between the object and thepulse wave measurer to a predetermined level, and after maintaining thecontact pressure at the level for a predetermined period of time, theapparatus 1300 for estimating cardiovascular information may decreasethe contact pressure.

The apparatus 1300 for estimating cardiovascular information may measurea first pulse wave signal and a second pulse wave signal from an objectby using light of different wavelengths in operation 1720, and maymeasure contact pressure between the object and the pulse wave measurerin operation 1730.

The apparatus 1300 for estimating cardiovascular information may extractcardiovascular characteristic values based on the first pulse wavesignal, the second pulse wave signal, and the contact pressure inoperation 1740, and may estimate cardiovascular information based on theextracted cardiovascular characteristic values in operation 1750.

FIG. 18 is a perspective diagram of a wrist-type wearable deviceaccording to another exemplary embodiment.

Referring to FIG. 18, the wrist-type wearable device 1800 includes astrap 1810 and a main body 1820.

The strap 1810 may be formed as a flexible band. However, this is merelyexemplary, and the strap 1810 is not limited thereto. That is, the strap1810 may be provided with various strap members which may be bent to bewrapped around a user's wrist.

The main body 1820 may include the above-described apparatuses 100 and1300 for estimating cardiovascular information. Further, the main body1820 may include a battery which supplies power to the wrist-typewearable device 1800 and the apparatuses 100 and 1300 for estimatingcardiovascular information.

The wrist-type wearable device 1800 may further include an inputinterface 1821 and a display 1822 which are mounted in the main body1820. The input interface 1821 may receive an input of various operationsignals from a user. The display 1822 may display data processed by thewrist-type wearable device 1800 and the apparatuses 100 and 1300 forestimating cardiovascular information, processing result data, and thelike.

Further, the main body 1820 may further include an actuator forcontrolling contact pressure between the pulse wave measurer and theobject. The actuator may control the contact pressure between the pulsewave measurer and the object by adjusting the length of the strap 1810.

While not restricted thereto, an exemplary embodiment can be embodied ascomputer-readable code on a computer-readable recording medium. Thecomputer-readable recording medium is any data storage device that canstore data that can be thereafter read by a computer system. Examples ofthe computer-readable recording medium include read-only memory (ROM),random-access memory (RAM), CD-ROMs, magnetic tapes, floppy disks, andoptical data storage devices. The computer-readable recording medium canalso be distributed over network-coupled computer systems so that thecomputer-readable code is stored and executed in a distributed fashion.Also, an exemplary embodiment may be written as a computer programtransmitted over a computer-readable transmission medium, such as acarrier wave, and received and implemented in general-use orspecial-purpose digital computers that execute the programs. Moreover,it is understood that in exemplary embodiments, one or more units of theabove-described apparatuses and devices can include circuitry, aprocessor, a microprocessor, etc., and may execute a computer programstored in a computer-readable medium.

The foregoing exemplary embodiments are merely exemplary and are not tobe construed as limiting. The present teaching can be readily applied toother types of apparatuses. Also, the description of the exemplaryembodiments is intended to be illustrative, and not to limit the scopeof the claims, and many alternatives, modifications, and variations willbe apparent to those skilled in the art.

What is claimed is:
 1. An apparatus for estimating cardiovascularinformation, the apparatus comprising: a communication interfaceconfigured to receive, from an external device, a cardiovascularinformation estimation model; a photoplethysmography (PPG) sensorconfigured to measure, from an object, a first pulse wave signal byusing a first light of a first wavelength and a second pulse wave signalby using a second light of a second wavelength, the first wavelengthbeing different from the second wavelength; a force sensor configured tomeasure a contact pressure between the object and the PPG sensor; and aprocessor configured to: detect a contact pressure transition period inwhich the contact pressure continuously increases or the contactpressure continuously decreases; extract a first valley point and asecond valley point, respectively from a first derivative signal of thefirst pulse wave signal and a second derivative signal of the secondpulse wave signal in the contact pressure transition period; determine,as a cardiovascular characteristic value, a change in the contactpressure during a time period from a first point in time correspondingto the first valley point of the first derivative signal, to a secondpoint in time corresponding to the second valley point of the secondderivative signal; and estimate blood pressure by inputting to thecardiovascular information estimation model that is received from theexternal device, the first valley point of the first derivative signal,the second valley point of the second derivative signal, and a rate ofthe change of the contact pressure over the time period from the firstpoint in time and the second point in time that correspond to the firstvalley point of the first derivative signal and the second valley pointof the second derivative signal, respectively.
 2. The apparatus of claim1, wherein the PPG sensor comprises: a light source configured to emitthe first light and the second light onto the object; and aphotodetector configured to measure the first pulse wave signal and thesecond pulse wave signal by receiving the first light and the secondlight which are reflected or scattered from the object, respectively. 3.The apparatus of claim 1, wherein the contact pressure transition periodcomprises a contact pressure increasing period during which the contactpressure continuously increases, and a contact pressure decreasingperiod during which the contact pressure continuously decreases.
 4. Theapparatus of claim 1, wherein the processor is further configured togenerate guide information for guiding a user to increase or decreasethe contact pressure when the object is in contact with the forcesensor.
 5. The apparatus of claim 1, further comprising an actuatorconfigured to control the contact pressure between the object and thePPG sensor.
 6. The apparatus of claim 1, wherein the communicationinterface is further configured to transmit, to the external device, atleast one of the first pulse wave signal and the second pulse wavesignal.
 7. The apparatus of claim 1, further comprising an outputinterface configured to output the blood pressure to the externaldevice.
 8. The apparatus of claim 1, wherein the apparatus isimplemented in a cellular phone or a smartphone.